BMD measurements of the spine derived from sagittal reformations of contrast-enhanced MDCT without dedicated software.

PURPOSE

To assess QCT equivalent BMD of the lumbar spine in sagittal reformations of routine abdominal contrast-enhanced MDCT with simple PACS measurement tools and to apply this method to MDCT datasets for differentiating patients with and without osteoporotic vertebral fractures.

MATERIALS AND METHODS

Eight postmenopausal women (65±5 years) underwent standard QCT to assess BMD of L1-L3. Afterwards routine abdominal contrast-enhanced MDCT images of these women were obtained and apparent BMD of L1-L3 was measured using the sagittal reformations. The MDCT-to-QCT conversion equation for BMD was calculated with linear regression analysis. The conversion equation was applied to vertebral BMD datasets (L1-L3) of 75 postmenopausal women (66±4 years). Seventeen of the 75 patients had osteoporotic vertebral fractures.

RESULTS

BMD values of contrast-enhanced MDCT were on average 56 mg/ml higher than those of standard QCT. A correlation coefficient of r=0.94 (p<0.05) was calculated for the BMD values of MDCT and standard QCT with the conversion equation BMDQCT=0.69×BMDMDCT-11 mg/ml. Accordingly converted BMD values of patients with vertebral fractures were significantly lower than those of patients without vertebral fractures (69 mg/ml vs. 85 mg/ml; p<0.05). Using ROC analysis to differentiate patients with and without vertebral fractures, AUC=0.72 was obtained for converted BMD values (p<0.05). Short- and long-term reproducibility errors for BMD measurements in the sagittal reformations amounted 2.09% and 7.70%, respectively.

CONCLUSION

BMD measurements of the spine could be computed in sagittal reformations of routine abdominal contrast-enhanced MDCT with minimal technical and time effort. Using the conversion equation, the acquired BMD data could differentiate patients with and without osteoporotic vertebral fractures.